Various automotive vehicle control systems such as forward obstacle detection systems or speed control systems for maintaining the distance to another vehicle, utilize sensors to detect objects in the vehicle path. In general, these sensors transmit a beam of defined width forward of the source vehicle and sense a reflection of the beam from a forward object such as a another vehicle. Typical sensors used in these systems include microwave radar sensors and infrared sensors.
If the forward looking sensor of these systems is fixed to look directly ahead of the source vehicle, it will effectively monitor the path of the source vehicle when the source vehicle's trajectory is a straight line. When the source vehicle's motion becomes curvilinear, there is an effective shift of the path of the source vehicle relative to the beam of the sensor. This effective shift is greater as distance increases within the maximum range of the sensor. This shift may result in the sensor not detecting a target in the source vehicle's path which is within the range of the sensor. Further, the sensor may detect false targets or clutter such as vehicles following different paths or guard rails adjacent the roadway which are ahead of the source vehicle but not within the source vehicle's path.
It has been proposed to maximize the useful range of the sensor and to avoid the detection of unwanted targets by steering the beam of the sensor, such as by rotating the antenna of a radar sensor, as the source vehicle travels through a curvilinear path. However, when the beam is steered so as to maximize the useful range of the sensor, there is a potential of a target vehicle within the source vehicle's path to become undetectable due to an effective lateral shift of the target vehicle out of the beam for some arc length of the curvilinear path as the range to the target vehicle decreases from the maximum range of the sensor along this path or not be detected such as when a target vehicle enters into this arc length of the source vehicle's path from another trajectory.